Steam boiler

ABSTRACT

A water-tube boiler for generating steam wherein the steam is generated in a circulatory system which is separated from and independent of the boiler&#39;&#39;s main steam drum. The boiler includes a plurality of header tubes which collectively define a fire chamber, and which serve both to distribute water to the main convection tubes for heating and to recirculate the unevaporated portion of the water through the system after the generated steam is drawn off. During each circulatory cycle in the header tubes, the generated steam is separated from the unevaporated portion of the water and drawn off to the main steam drum where it is collected prior to discharge.

United States Patent OConnor 1 Nov. 21, 1972 [54] STEAM BOILER [72] Inventor: Chadwell OConnor, 3490 East Primary Examiner xenneth P Foothill Boulevard, Pasadena, Calif Attorney-Wolfe, Hubbard, Leydlg, Volt & Osann, 91107 [22] Filed: Feb. 19, 1971 57 ABSTRACT [21] Appl' 116944 A water-tube boiler for generating steam wherein the steam is generated in a circulatory system which is [52] U.S. Cl. ..l22/235 R, 122/336 separated from and independent of the boilers main [51] Int. Cl ..F22b 21/00 steam drum. The boiler includes a plurality of header Field of Search ..l22/235 R, 235 J, 336, 48 tubes which collectively define a fire chamber, and

122/489 which serve both to distribute water to the main convection tubes for heating and to recirculate the [56] References cued unevaporated portion of the water through the system UNITED STATES PATENTS after the generated steam is drawn off. During each circulatory cycle 1n the header tubes, the generated SChmldt team is eparated from the unevaporated portion of 1,903,515 4/1933 Monroe ..122/488 X the water and drawn off to the main Steam drum 2,146,261 2/1939 Krug ..l22/235 where i i collected prior to discharge 2,265,481 12/1941 Hartmann ..122/489 2,741,228 4/1956 Vorkauf ..l22/488 X 9 Claims, 8 Drawing Figures PNENTEDNUVZI I972 SHEET 1 OF 4 ww y PATENT ED luv 2 1 I972 SHEET U 0F 4 M M r W (My?! aka/x? r wz ZZZ/m STEAM BOILER DESCRIPTION OF THE INVENTION This invention relates generally to steam generating apparatus and, more particularly, to an improved water-tube type steam boiler.

As a rule, the amount of water circulated through a water-tube type steam boiler is four times the amount evaporated into steam. In the past, the tube steam in boilers of this type was connected directly or via headers to a main steam drum, and the circulating water was passed through the main steam drum during each circulating cycle. Since the main steam drum is the primary separating device in this arrangement for separating the steam from the water, there is considerable turbulence in the drum and this turbulence results in poor separation between the water and the steam being drawn off. This is generally undesirable because wet steam reduces engine efficiency. A further disadvantage in the arrangement where the tubes go directly to the steam drum is that the large number of conduits being fitted directly into the main steam drum results in a low weld efficiency at the drum and thus requires a relatively thick drum wall for withstanding any given pressure.

Accordingly, it is the primary aim of the present invention to provide an improved water-tube type steam boiler which is capable of providing a better quality steam than provided by water-tube type steam boilers used heretofore.

A further object of the invention is to provide a steam boiler of the foregoing type wherein unevaporated water can be recirculated in the headers without being returned to the main steam drum.

Another object of the invention is to provide a steam boiler of the foregoing type wherein the header system defines a fire chamber and serves as the primary separating device for separating the steam from the unevaporated water.

Still another object of the invention is to provide a steam boiler of the foregoing type which is relatively economical to construct yet capable of withstanding high pressures.

Other objects and advantages of the invention will become apparent upon reading the following detailed description and upon reference to the drawings, in which:

FIG. 1 is a perspective of a steam boiler constructed in accordance with the invention;

FIG. 2 is a fragmentary perspective of the steam boiler shown in FIG. 1 with portions of the housing and the headers removed;

FIG. 3 is an enlarged side elevation of the steam boiler as shown in FIG. 2 with the housing completely removed;

FIG. 4 is a section taken substantially in the plane of line 44 in FIG. 3;

FIG. 5 is an end elevation taken along line 5-5 in FIG. 3, with the complete headers;

FIG. 6 is a section taken substantially in the plane of line 6-6 in FIG. 3;

FIG. 7 is a section taken substantially in the plane of line 77 in FIG. 5; and

FIG. 8 is a cut-away schematic of a steam boiler constructed in accordance with the invention.

While the invention is susceptible to various modifications and alternative forms, a preferred embodiment thereof has been shown in the drawings which will be described in detail herein. It should be understood, however, that it is not intended to limit the invention to the particular form disclosed but, to the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the invention.

Referring to the drawings, the present invention presupposes a natural circulation boiler wherein the heated water circulates counterclockwise (as viewed in FIG. 8) as a result of the heating process. As in other steam boilers of the water-tube type, the water used in generating the steam is evaporated in a circulatory system 13 which is exposed to the radiant heat of burning gases; and the generating steam is collected in a main steam drum 14 from which it is then discharged for use. To minimize the amount of water carried away by the discharged steam, a pair of baffle plates 44 and 45 are mounted within the main steam drum 14, in the illustrated embodiment, and positioned to impart a circulating motion to the steam collected in the drum, prior to discharge. It will be noted in connection herewith, that the steam discharge nozzle 47 is positioned with respect to the baffles so as to assist in the swirling motion caused by deflecting the steam between the respective baffle plates 44 and 45.

In accordance with the invention, the main circulatory system 13 of the steam boiler 10 is separated from and independent of the main steam drum 14. Thus in the preferred embodiment, a plurality of U-shaped header tubes 20-33, positioned on their sides and mounted by means of metal strips to a pair of angle irons 11 and 12, are provided for distributing water to a plurality of convection tubes 16 prior to heating and for recirculating the unevaporated portion of the water after the generated steam is separated therefrom. The convection tubes 16, each of which has a respective inlet and outlet end, are located between the projecting legs of the respective U-shaped header tubes 20-33 and are operatively positioned for exposure to a heat' supply. Further, each of the convection tubes 16 is connected at both of its respective ends to one of the individual header tubes 20-33 so as to combine therewith to form a closed circulatory loop through which water can be circulated and wherein steam can be generated. In connection herewith it should be noted that the convection tubes 16, in the illustrated embodiment, are sharply bent at right angles. This is done both to provide for expansion and to fit as much tube length as possible within the available space.

Further, it should be noted that inspection plugs 42 are respectively provided on each end of the U-shaped header tubes 20-33. These inspection plugs 42 provide access to the inside of the respective headers and eliminate the need for the mud drum commonly found in water-tube boilers. By opening these plugs, it becomes a simple matter to check for and remove accumulations of foreign matter which tend to build-up in the headers and restrict the flow of water and steam therein.

In keeping with the invention, the individual closed circulatory loops formed respectively by the U-shaped headers 20-33 and the convection tubes 16 are independent of and separated from the boilers steam drum. To this end, the steam drum 14, which serves to hold a supply of water 34 for the boiler and to collect the steam generated in the respective circulatory loops, is mounted atop the circulatory system 13 and separately connected to the individual header tubes -33 via a plurality of pairs of pipes 36 and 37. Accordingly, since the unevaporated portion of the water can be recirculated, in the headers 20-33 without passing it through the steam drum 14, there is less turbulence in the drum l4 and, accordingly, it is possible in the present invention to obtain a drier steam than was heretofore possible in water-tube boilers. Further, by having only a relatively few small pipes 36 and 37 going directly into the steam drum 14, the weld efficiency of the drum is higher and, as a result, the drum itself does not have to be as thick to withstand a given pressure.

The operation of a steam boiler constructed in accordance with the invention can more clearly be understood by referring to FIG. 8 which schematically illustrates water and steam flowing in the boiler 10. Water is introduced into the boiler 10 via an inlet nozzle 35 which communicates with the steam drum 14 and is distributed from the steam drum 14 to the respective header tubes 20-33 via the plurality of pipes 36 in order to constantly replenish the supply of circulating water as steam is drawn off. As the water circulates it is heated in the convection tubes 16 causing approximately one quarter of it to evaporate into steam. The unevaporated portion of the water together with the generated steam continues to circulate through the boiler flowing slightly uphill towards the respective upper corners of the individual header tubes 20-33. As the mixture of steam and water reaches the location near the upper corner of respective headers where the plurality of pipes 37 are connected, the steam is separated from the unevaporated water flowing in the respective headers and drawn off through the respective pipes 37 to the main steam drum 14 where it is collected prior to discharge.

it should be noted in connection herewith that there is practically no circulation of water through the drum with this arrangement. Accordingly, the steam drum 14 can be relatively small for a boiler of any given capacity. If the economy of having a smaller drum is not desired, however, the present design still permits the use of a larger drum, which due to its greater relieving area will enable the production of a higher quality steam than would the more economical smaller drum.

In accordance with another aspect of the invention, the U-shaped header tubes 20-33 are constructed from a heavy gauge pipe and operatively aligned in parallel planes respectively adjacent to one another so as to collectively form three of the side walls of a rectangular fire chamber 40 which is located within the area defined by the projecting legs of the respective header tubes 20-33. A row of individually aligned partition wall tubes 55 are connected across the ends of the individual header tubes 20-33 to form the fourth side wall of the tire chamber 40. Similarly, two rows of screen tubes 64, positioned respectively along the first header tubes 20 on the left hand side of the boiler 10 and alternately along the last two header tubes 32 and 33 on the right hand side of the boiler (as viewed in FIG. 4), form the respective end walls 60 and 61. In

connection herewith, it will be noted that the end three screen tubes 64 associated with the left hand header 20 are offset to provide an inlet through which a stream of burning gas can be directed into the fire chamber 40. Further it will be noted that the partition wall tubes 55 are heavier than the other convection tubes 16 and that each of these tubes is provided along its length with a pair of outwardly extending fins 58 of sufficient width to abut the fins on the next adjacent tubes 55 so as to form a solid barrier.

This design is advantageous since it permits the construction of a pressurized furnace. The U-shaped headers 20-33 present sturdy furnace walls and can easily be sealed to create a strong fire chamber 40 which is capable of withstanding high pressure. The significance in this is that the boiler configuration is readily adapted to be embodied as an adjunct to various industrial process which generate waste heat. Since, industrial processes will normally produce a hot gas discharge which is under considerable pressure, the idea here is to use a small boiler of this type in line with the normally discharged waste gas so as to reclaim some of the heat in the form of usable steam.

In the illustrated embodiment, however, the steam boiler 10 is intended to be a self-containing unit. Accordingly, the entire boiler 10 is enclosed with an insulating material 38 and a gas burner 39 is attached to the side of the boiler 10 and positioned for directing a stream of burning gas into the fire chamber 40.

To insure maximum heating efficiency in the boiler and to prevent the formation of soot on the convection tubes 16, a second row 56 of partition wall tubes 55, connected between the projecting legs of the individual header tubes 20-30, are provided in the preferred construction for isolating the angled convection tubes from direct contact with the luminous portion of the gas flames. Thus, referring to FIG. 4, the gas entering the main portion of the fire chamber 40 is channeled to the back wall 61 of screen tubes 64 where it is turned around the right hand end of the second row 56 of partition wall tubes 55. In this manner, the gas flows through the main convection tubes 16 while at its highest temperature and is then discharged from the boiler 10 via an exhaust stack 65.

Turning to another aspect of the invention, in order to increase the output temperature of the steam generated in the boiler 10 and to insure that the steam is constant in temperature when delivered for use, a superheater tube 67 is connected to the discharge nozzle 47 of the main steam drum l4 and positioned adjacent the outer surface of the back wall 61 of the tire chamber 40, i.e., the wall formed by the screen tubes 64. As the steam travels back and forth through the superheater tube 67 (H6. 7) it is exposed to both the convection and the radiant heat of the gas burning in the fire chamber 40 causing the temperature of the superheated steam to remain constant through varying loads. Those skilled in the art will appreciate the difficulties encountered in servicing superheater tubes in steam boilers heretofore and will recognize the advantages of the present invention in positioning the superheater tube 67 between the screen tubes 64 and a thin layer of refractory material adjacent to the insulated wall 38 in order to have it relatively accessible for servicing rather than positioning it internally within the boiler. That is, in the present construction the entire superheater tube 67 can be easily exposed by simply removing the one section of refractory and insulating material adjacent the back wall 61.

I claim as my invention:

1. An improved steam boiler including in combination, a steam drum for holding a supply of water for the boiler and for collecting generated steam; a plurality of convection tubes operatively positioned for exposure to a heat supply, each of said convection tubes having a respective inlet and outlet end; and a plurality of headers positioned with respect to the steam drum so that the upper portions thereof are substantially below the normal operating level of said water supply, each of said headers individually communicating with the steam drum for receiving water from said drum and for conducting steam to said drum, each of said headers also being connected to both ends of each ofa group of said plurality of convection tubes so that each header and the convection tubes connected thereto form a close circulatory loop independent of said steam drum whereby water is recirculated through said headers and convection tubes without passing through said steam drum.

2. A steam boiler as set forth in claim 1 wherein the individual headers are U-shaped and operatively aligned in parallel planes respectively adjacent to one another so as to collectively form side walls of a fire chamber defined thereby.

3. A steam boiler as set forth in claim 2 further comprising a plurality of inspection plugs respectively attached to each end of the individual headers so as to enable the easy removal of foreign material accumulated therein.

4. An improved water-tube type steam boiler including, in combination: a steam drum for holding a supply of water for the boiler and for collecting generated steam; a plurality of convection tubes, each having a respective inlet and outlet end and being operatively positioned for exposure to a heat supply; a plurality of looped headers aligned in parallel planes respectively adjacent to one another so as to collectively form side walls of a fire chamber defined thereby, each of said headers individually communicating with the steam drum for receiving water from said drum and for conducting steam to said drum, each of said headers also being connected to both ends of each of a plurality of said convection tubes so that each header and the convection tubes connected thereto form a closed circulatory loop independent of said steam drum whereby water is recirculated through said headers and convection tubes without passing through said steam drum; and a plurality of screen tubes each having an inlet and an outlet end respectively, a first group of said plurality of screen tubes being individually connected at both ends to the header at one end of said group of adjacently aligned headers and a second group of said plurality of screen tubes being individually connected at both ends to the header at the other end of said group of adjacently aligned headers, so as to form the respective end walls for the fire chamber.

5. A steam boiler as set forth in claim 4 wherein the individual screen tubes associated with one of said end headers are respectively shaped to form an opening in the respective side wall to permit the introduction of a heat source therethrough.

6. A steam boiler as set forth in claim 4 further comprising a superheater tube communicating with the steam drum and positioned adjacent to the outwardly facing surface of the plurality of screen tubes associated with the other of said end headers.

7. A steam boiler as set forth in claim 4 further comprising a housing made of a insulating material and enclosing the entire boiler.

8. In a water-tube boiler for generating steam, including a steam drum for holding a supply of water for the boiler and for collecting generated steam, a plurality of convection tubes operatively positioned for exposure to a heat supply, and a plurality of looped headers individually connected to respective groups of the plurality of convection tubes and communicating with the steam drum for receiving water from the drum and for conducting steam to the drum, the improvement wherein said plurality of headers are operatively aligned in parallel planes respectively adjacent to one another so as to collectively form side walls of a fire chamber defined thereby.

9. In a water-tube type steam boiler, including: a steam drum for holding a supply of water for the boiler and for collecting generated steam; a plurality of convection tubes operatively positioned for exposure to a heat supply; a plurality of looped headers aligned in parallel planes respectively adjacent to one another so as to collectively define a fire chamber, each of said headers individually connected to respective groups of the plurality of convection tubes and communicating with the steam drum for receiving water from the drum and for conducting steam to the drum; and a superheater tube connected to the steam drum for passing the collected steam from the boiler, the improvement wherein said superheater tube is positioned external of and adjacent to an end wall of said fire chamber so as to be relatively accessible for service while still being sufficiently exposed to both the convection and the radiant heat of the gases burning within the fire chamber so as to increase the temperature evenly of the stem flowing therein. 

1. An improved steam boiler including in combination, a steam drum for holding a supply of water for the boiler and for collecting generated steam; a plurality of convection tubes operatively positioned for exposure to a heat supply, each of said convection tubes having a respective inlet and outlet end; and a plurality of headers positioned with respect to the steam drum so that the upper portions thereof are substantially below the normal operating level of said water supply, each of said headers individually communicating with the steam drum for receiving water from said drum and for conducting steam to said drum, each of said headers also being connected to both ends of each of a group of said plurality of convection tubes so that each header and the convection tubes connected thereto form a close circulatory loop independent of said steam drum whereby water is recirculated through said headers and convection tubes without passing through said steam drum.
 1. An improved steam boiler including in combination, a steam drum for holding a supply of water for the boiler and for collecting generated steam; a plurality of convection tubes operatively positioned for exposure to a heat supply, each of said convection tubes having a respective inlet and outlet end; and a plurality of headers positioned with respect to the steam drum so that the upper portions thereof are substantially below the normal operating level of said water supply, each of said headers individually communicating with the steam drum for receiving water from said drum and for conducting steam to said drum, each of said headers also being connected to both ends of each of a group of said plurality of convection tubes so that each header and the convection tubes connected thereto form a close circulatory loop independent of said steam drum whereby water is recirculated through said headers and convection tubes without passing through said steam drum.
 2. A steam boiler as set forth in claim 1 wherein the individual headers are U-shaped and operatively aligned in parallel planes respectively adjacent to one another so as to collectively form side walls of a fire chamber defined thereby.
 3. A steam boiler as set forth in claim 2 further comprising a plurality of inspection plugs respectively attached to each end of the individual headers so as to enable the easy removal of foreign material accumulated therein.
 4. An improved water-tube type steam boiler including, in combination: a steam drum for holding a supply of water for the boiler and for collecting generated steam; a plurality of convection tubes, each having a respective inlet and outlet end and being operatively positioned for exposure to a heat supply; a plurality of looped headers aligned in parallel planes respectively adjacent to one another so as to collectively form side walls of a fire chamber defined thereby, each of said headers individually communicating with the steam drum for receiving water from said drum and for conducting steam to said drum, each of said headers also being connected to both ends of each of a plurality of said convection tubes so that each header and the convection tubes connected thereto form a closed circulatory loop independent of said steam drum whereby water is recirculated through said headers and convection tubes without passing through said steam drum; and a plurality of screen tubes each having an inlet and an outlet end respectively, a first group of said plurality of screen tubes being individually connected at both ends to the header at one end of said group of adjacently aligned headers and a second group of said plurality of screen tubes being individually connected at both ends to the header at the other end of said group of adjacently aligned headers, so as to form the respective end walls for the fire chamber.
 5. A steam boiler as set forth in claim 4 wherein the individual screen tubes associated with one of said end headers are respectively shaped to form an opening in the respective side wall to permit the introduction of a heat source therethrough.
 6. A steam boiler as set forth in claim 4 further comprising a superheater tube communicating with the steam drum and positioned adjacent to the outwardly facing surface of the plurality of screen tubes associated with the other of said end headers.
 7. A steam boiler as set forth in claim 4 further comprising a housing made of a insulating material and enclosing the entire boiler.
 8. In a water-tube boiler for generating steam, including a steam drum for holding a supply of water for the boiler and for collecting generated steam, a plurality of convection tubes operatively positioned for exposure to a heat supply, and a plurality of looped headers individually connected to respective groups of the plurality of convection tubes and communicating with the steam drum for receiving water from the drum and for conducting steam to the drum, the improvement wherein said plurality of headers are operatively aligned in parallel planes respectively adjacent to one another so as to collectively form side walls of a fire chamber defined thereby. 